Manuscript Summary: The Directorium perpetuum of the monastery of St. Gall, commissioned by Abbot Franz von Gaisberg (1504–1529), consists of seven volumes (Cod. Sang. 533–539). A total of 36 regulae contain the liturgical rules for the Liturgy of the Hours for all possible annual calendars, due to the variable date of Easter. Each rule begins with Epiphany; the rules for the holidays of the Christmas season until the Vigil of Epiphany (which do not depend on the date of Easter) are compiled in Cod. Sang. 539. Cod. Sang. 535 contains the 11th through 17th rules, for when Easter falls between the 1st and the 7th of April (reference date in the codex: Septuagesima, January 28th to February 3rd). The illumination of the manuscript is by Nikolaus Bertschi from Rorschach and an assistant: p. 6 contains a full-page miniature (at the top a Lamentation of Christ, below Saint Gall and Saint Othmar supporting the coat of arms), p. 6a, 54, 108, 164, 211, 263 and 317 contain initials in opaque colors (p. 164 on a background of gold leaf) with scrolls or richly decorated borders. This volume was written by the St. Gall cathedral organist Fridolin Sicher. (sno)